Lateral Ankle Sprain that affects lateral ankle ligaments is the most common injuries of the ankle joint that represent 85% of ankle ligament sprains.

There are two types of which:

  1. High Ankle Sprain (1-10% of all ankle sprains)
  2. Low Ankle Sprain (>90% of all ankle sprains).

In the younger population, serious ankle sprains are unusual in the skeletally immature, because the ligaments are usually stronger than the bone, necessitating a physeal fracture to be ruled out.

The ATFL, which is the least elastic of the lateral ligaments, is involved in 60–70% of all ankle sprains, while 20%
involve both the ATFL and the CFL.

The sequence of lateral ligament tears is first the ATFL, then the anterolateral capsule, then the distal tibiofibular ligament, then the CFL, and finally the PTFL, the strongest of the lateral ligaments.

Lateral Malleolus Anatomy

Lateral Malleolus is the distal part of the fibula, it articulates with the tibia and the talus bone.

There are many ligaments on the lateral side of the ankle joint (lateral collateral ligament complex) that is involved in lateral ankle sprain:

  1. Anterior Talofibular Ligament (ATFL)
  2. Calcaneofibular Ligament (CFL).
  3. Posterior Talofibular Ligament (PTFL)
  4. Lateral Talocalcaneal Interosseous (LTCIL).

Another ligament complex is the Syndesmosis ligaments that connect the fibula with tibia distally, these ligaments are:

  1. Anterior-inferior tibiofibular ligaments (AITFL)
  2. posterior-inferior tibiofibular ligament (PITFL)
  3. Interosseous membrane
  4. Interosseous ligament (IOL)
  5. Inferior transverse ligament (ITL).

You can read more details of these ligaments in Ankle Anatomy.

Lateral Ankle ligaments anatomy
lateral ankle ligaments anatomy

Lateral Ankle Sprain Grades

Lateral ankle sprain can be categorized as follows:

Grade I:

Grade I is characterized by minimal to no swelling and localized tenderness over the ATFL. These sprains require
on the average 11.7 days before the full resumption of athletic activities.

Grade II:

Grade II is characterized by localized swelling and more diffuse lateral tenderness. These sprains require approximately 2–6 weeks for return to full athletic function.

Grade III:

Grade III is characterized by significant swelling, pain, and ecchymosis and should be referred to a specialist.

Grade III injuries may require greater than 6 weeks to return to full function. For acute grade III ankle sprains, the average duration of disability has been reported to be anywhere from 4.5 to 26 weeks, and only 25–60% of patients are symptom free 1–4 years after injury.

In a summary of all prospective and controlled studies on grade III sprains, it was concluded that the long-term prognosis is good to excellent in 80–90% of patients with this injury, regardless of the type of intervention chosen.

The West Point Lateral Ankle Sprain Grading System:

CriterionGrade IGrade IIGrade III
Location of tendernessATFLATFL and CFLATFL, CFL, and PTFL
Edema and ecchymosisSlight and localModerate and localSignificant and diffuse
Weight-bearing abilityFull or partialDifficult without crutchesImpossible without significant pain
Ligament damageStretchedPartial tearComplete tear
InstabilityNoneNone or slightDefinite
West Point Ankle Sprain Grading
West Point Lateral Ankle Sprain Grading

Physical Examination

Although a physical examination is reliable for the diagnosis of an ankle fracture, the reliability for detecting lateral ankle sprain may not be as definitive, especially if the examination is performed immediately after the injury.

No single symptom or test can provide a completely accurate diagnosis of a lateral ankle ligament sprain or rupture, but the collection of these findings can be strongly indicative:

  1. The absence of swelling at the time of the delayed (after 4 days) physical examination suggests that there is no ligament rupture, whereas extensive swelling at this time is indicative of ligament rupture.
  2. Pain on palpation of the involved ligament suggests involvement.
  3. Presence of a hematoma suggests a rupture.
  4. Positive anterior drawer test is also a lateral ankle sprain test.
  5. Impairment of walking ability after injury suggests involvement.
See Also: Anterior Drawer Test of the ankle

One study demonstrated that a combination of tenderness at the level of the ATFL, a lateral hematoma, discoloration, and a positive drawer test indicated a ligament rupture in 95% of cases, whereas the absence of these findings always indicated an intact ligament.

The specificity and sensitivity of delayed physical examination for the presence or absence of a lateral ligament injury were 84% and 96%, respectively, indicating that a reasonably precise clinical diagnosis is possible if the examination is delayed for approximately 4 days postinjury.

A clinician examining the foot and ankle needs to be aware of other potential pathologies to consider when an adolescent patient is referred to physical therapy with the diagnosis of ankle sprain. These pathologies include:

  1. osteochondrosis,
  2. osteochondritis dissecans,
  3. accessory ossicle,
  4. anterior impingement syndrome,
  5. sinus tarsi syndrome,
  6. tarsal coalition,
  7. epiphyseal fractures.
See Also: Posterior Drawer Test of the ankle

Radiology

Recommended X-ray views include:

  • AP, mortise, and lateral x-rays of the ankle obtained; weight-bearing x-ray preferable if patient can tolerate.
  • Foot x-rays should be obtained if any pain on examination, especially at base of fifth metatarsal or anterior process of calcaneus to rule out fracture.
Lateral Ankle Sprain imaging
Lateral Ankle Sprain Xray

MRI typically reserved for patients with continued pain despite weeks of conservative treatment (immobilization, elevation, ice, NSAIDs) or concern for loose body or osteochondral defect.

MRI findings include:

  • MRI may demonstrate attenuation or tear of the lateral ligamentous structures.
  • Bone bruising common in severe sprains and may result in longer time to pain-free activity and return to sports
Lateral Ankle Sprain MRI
CFL ligament tear – MRI

Ottawa ankle rules:

Ottawa ankle rules (Stiell et al., 1995) dictate radiographs appropriate only if:

  1. tenderness at distal tibia or fibula,
  2. tenderness at base of fifth metatarsal or navicular,
  3. inability to bear weight

Associated conditions

Lateral Ankle Sprain may be associated with:

  1. ankle dislocation,
  2. distal lateral malleolar avulsion or spiral fracture,
  3. medial malleolar fracture,
  4. talar neck or medial compression fractures.

Most (86%) ankle ligament tears are midsubstance; thus, only 14% are avulsion injuries.

Potential Pathologies Associated with Adolescent Ankle Injuries:

PathologyDefinitionSigns and Symptoms
Sever ostoechondrosisCalcaneal apophysitisLocalized pain and tenderness at the Achilles attachment
Talocrural osteochondritis dissecansInjury to articular cartilage and/or underlying boneCatching, locking, and/or sudden sharp stabbing pains
Accessory ossicles at the distal tiba or fibulaOssification centers that have not fusedLocalized pain and tenderness
Accessory bone with rounded edges on radiographs
Accessory os trigonum Accessory ossicle on the posterior-lateral process of the talusPain posteriorly with maximum plantar flexion
Accessory bone with rounded edges on radiographs
Anterior ankle impingementThickening of joint capsule with or without bone spurs at the anterior talocrural joint
Pain anteriorly with sudden dorsiflexion
Decreased dorsiflexion ROM, a hard end-feel if bone spurs are present
Sinus tarsus syndromeInjury to the structures contained within the sinus tarsusHindfoot instability
Tenderness inferior and anterior to the anterior talofibular ligament
tarsal coalitionCongenital union between two tarsal bones: usually calcaneonavicular or talocalcaneal coalitionLocalized tenderness over the involved joint
Rigid flatfoot and peroneal muscle spasm with inversion
Distal tibal epiphyseal fracturesGrowth plate injury Tenderness at the distal tibia
Inability to weight bear
Potential Pathologies Associated with Adolescent Ankle Injuries

Nonoperative treatment:

Nonoperative treatment of lateral ankle sprain include the RICE protocol:

  1. Rest,
  2. ice,
  3. compression,
  4. elevation.

Protected weight-bearing with an orthosis is permitted, with weight-bearing to tolerance as soon as possible following injury.

The lateral ankle sprain healing time depends on the severity of the injury, it sometimes takes from several weeks (3-4 weeks) to about 3 months before ligament healing occurred.

Physical therapy:

Physical therapy is important for balance and proprioception, peroneal strengthening, and associated with a decreased rate of reinjury.

As the healing progresses and the patient is able to bear more weight on his or her ankle, there is a corresponding increase in the use of weight-bearing (closed-chain) exercises. A recommended activity during this phase is the “cross drill.”

One of the lateral ankle sprain exercises is that the patient stands independently or with minimal assistance on the involved limb, with the other leg flexed. The patient then moves the uninvolved limb into hip flexion, hip extension, hip abduction, and hip adduction. The exercise is performed initially on a firm surface with the eyes open, and then, as the patient improves, the exercise is performed on a foam surface or balance board, first with the eyes open and then with the eyes closed.

Subacute stages:

In the subacute stages of the lateral ankle sprain rehabilitation process (4–14 days), the patient begins dynamic balance and proprioceptive exercises. Using a balance board, the patient balances on the involved limb, while playing ” catch ” with the clinician.

Long-sitting gastrocnemius stretching with a strap or sheet can be introduced in this phase to promote ankle dorsiflexion past the neutral position, enabling a closer to normal walking pattern.

Open-chain (non– weight-bearing) progressive resistive exercises with elastic resistance are performed for isolated plantar flexion, dorsiflexion, inversion, and eversion.

Stationary cycling can also be performed (at a comfortable intensity for up to 30 minutes), to provide cardiovascular endurance training and controlled ankle ROM.

Advanced healing stage:

In the advanced healing stage of the lateral ankle sprain rehabilitation (2–4 weeks postinjury), the goals are as follows:

  1. the restoration of normal AROM;
  2. normal gait without an assistive device;
  3. pain-free performance of full-weight-bearing functional activities;
  4. enhancement of proprioception.

Activities to help achieve these goals include:

  1. heel-to-toe anterior–posterior walking.
  2. carioca drills,
  3. mini-trampoline balancing exercises (unilateral stance with eyes open and then closed, and catching and passing activities with a medicine ball).

Lateral Ankle Sprain Rehabilitation Exercises:

Operative treatment:

Operative treatment of lateral ankle sprain is reserved for patients with recurrent and symptomatic instability with excessive and asymmetric talar tilt and positive anterior drawer test, symptomatic osteochondral defects.

Multiple procedures described; anatomic procedures typically first-line treatment and successful in 85% to 90% of cases.

Modified Bröstrom procedure, anatomic reconstruction of ATFL supplemented with extensor retinaculum, while nonanatomic, peroneal tendon procedures (Evans procedure, Chrisman-Snook) or allograft procedures are reserved for recurrent instability after initial operative treatment.

Lateral Ankle Sprain treatment - Modified Bröstrom procedure
Modified Bröstrom Procedure

High Ankle Sprain

This type involves the Syndesmosis ligaments, and it requires nearly twice as long to return to activity as “low” ankle
sprains.

The mechanisms of injury for syndesmotic ankle sprains include:

  • forceful external rotation of the foot, resulting in widening of the ankle mortise, as the talus is driven into external rotation within the ankle mortise;
  • forceful eversion of the talus, which widens the mortise;
  • forceful dorsiflexion, which widens the mortise, as the wider anterior aspect of the talar dome enters the joint space.

With all of the above mechanisms, the distal fibula is pushed laterally away from its articulation with the distal tibia.

Pain in the anterior syndesmosis with syndesmosis squeeze or external rotation stress tests suggestive of injury.

Radiology

Radiographic recommended views include:

  1. AP and lateral,
  2. mortise view of ankle,
  3. external rotation stress radiograph
  4. gravity stress view.

Radiographic findings include:

  1. Decreased tibiofibular overlap (normal >6 mm on AP view and >1 mm on mortise view)
  2. Increased medial clear space (normal less than or equal to 4 mm)
  3. Increased tibiofibular clear space (normal <6 mm on both AP and mortise views).

CT and MRI is indicated if there is a clinical suspicion of syndesmotic injury with normal radiographs.

Syndesmotic Ankle Sprain Treatment

Stable injuries may be treated with RICE (Rest – Ice – Compression – Elevation)

Unstable injuries treated with operative intervention, especially in athletic population (syndesmosis screw fixation – syndesmosis fixation with suture button).

Chronic instability of the syndesmosis may then result in increased shear stress and altered contact pressure patterns that might predispose the individual to degenerative articular cartilage changes in the ankle joint.

Recurrent Ankle Sprain

Recurrent lateral ankle sprain causes may include the following:

  1. healing of the ligaments in a lengthened position;
  2. weakness of the healed ligaments due to inherent weakness of the scar;
  3. fibular (peroneal) muscle weakness (the incompletely rehabilitated ankle sprain);
  4. distal tibiofibular instability;
  5. hereditary hypermobility;
  6. loss of ankle proprioception;impingement by the distal fascicle of the anterior tibiofibular ligament, and/or impingement of capsular scar tissue (meniscoid tissue) in the talofibular joint;
  7. undiagnosed associated problems such as cuboid subluxation or subtalar instability.

Chronic lateral instability is manifested by recurrent injuries with pain, tenderness, and sometimes bruising over the lateral ligaments.

In general, subjective complaints include:

  1. frequent sprains.
  2. difficulty in running on uneven surfaces.
  3. difficulty in cutting and jumping in athletic events.
  4. feelings of “giving way”.
  5. Recurrent pain and swelling.
  6. Tenderness
  7. Inability to run.
  8. Weakness.

Recurrent ankle sprains are typically treated conservatively for 2–3 months, using a combination of some or all of the following:

  1. a lateral heel wedge,
  2. fibular (peroneal) muscle strengthening,
  3. proprioceptive/coordination exercises,
  4. taping,
  5. elastic or thermoplastic ankle supports,
  6. a short leg brace.

If the conservative trial fails late repair or reconstruction of the lateral ligaments is recommended.

A number of conditions can mimic ankle instability:

  1. Fibularis (peroneal) tendon subluxation.
  2. Instability of the Chopart joint. Inversion and plantar flexion trauma of the foot may result in avulsion by the bifurcate ligament and, sometimes, additionally by the talonavicular ligament. Injuries at the Chopart joint level are, however, frequently missed acutely and misdiagnosed as lateral ankle sprain, if the clinical examination is not carefully carried out.
  3. Talocalcaneal and talonavicular coalition.
  4. Posterior tibial dysfunction.

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